Highly compact AC-AC converter achieving a high voltage transfer ratio

This paper reports a new, highly integrated modular design approach for pulsewidth-modulation ac-ac converters based on a modular phase-bank structure. Novel high-power 3-in-1 integrated bi-directional power modules (IBPM) rated at 1200-V ac and 150 A and the 3-to-1 phase bank circuits have been successfully developed, fabricated, and tested. This enables the modularity design of the multiphase converter systems and reduces the critical parasitic inductance. A theoretical analysis of the IBPM's silicon utilization for this new breed of direct power converters has been outlined. A lab prototype at medium power level has been successfully designed, implemented, and tested with good results. A nearly 460-Vrms out voltage at a 1: 0.955 voltage transfer ratio, which, perhaps, is the highest performance reported so far in the literature, has been achieved by the novel two-side modulation control system. The converter-fed ac motor system is able to operate over the 0-240-Hz range with inherent regenerative capability and four-quadrant operation. Potential industrial applications are also briefly highlighted in this paper.